Maths lessons sent from the Outback by the Overland Australia team of Expedition 360 for use by classrooms worldwide free of charge.

Animal Moisture Loss Calculations

Sunday, 2001, August 26. On the Plenty 'Highway', fifty kilometres east
of Jervois Station.

Despite what might seem to be an advantage in a largely barren
ecosystem, a small creature's survival in the desert can be more
difficult than that of a large animal. Although they do not have the
need for great amounts of water, they require water more often, both
because their bodies do not have the capability to store it, and
because they lose a greater percentage through the skin (or other body
covering). Termites must keep humidity levels inside their mounds and
underground work areas very high to prevent desiccation.

Imagine an 80 kilogram person shrinking to the size of a termite - 8
milligrams. That person would have 200 times more surface area compared
to their volume. Having that much less protected flesh would mean that
they would be losing 200 times as much moisture in the same level of
humidity.

Suggested learning activities: using these figures, work out how much
water loss your own pet, or the average pet dog (10kg) or cat (3kg) or
bird (100g), might have compared to a human. Find the average weights
of different animals; and try this with them. How much less water per
kilogram might an elephant need, under the same conditions?